Benthic-Pelagic state changes in the primary trophic level of an ancient tropical lake

Mariam K. Ageli, Paul B. Hamilton, Andrew J. Bramburger, R. Paul Weidman, Zhuoyan Song, James Russell, Hendrik Vogel, Satria Bijaksana, G. Douglas Haffner

Research output: Contribution to journalArticlepeer-review

Abstract

Many large, ancient lakes support primarily planktonic-driven food webs. In contrast, the lowest trophic levels of the Malili Lakes of Sulawesi Island, Indonesia are dominated by benthic diatom communities composed mainly of endemic species. Centric diatoms are not observed in the current diatom assemblage and pennate pelagic species are rare. Using two deep drill-cores from Lake Towuti, we investigated whether the lake has always been dominated by benthic primary production. Despite the ultra-oligotrophic conditions observed in the lake today, we observed state changes characterized by productive planktonic communities and less productive, benthic-dominated diatom assemblages. Two periods of planktonic production, each lasting approximately 50 kyr, were dominated by a complex mixture of Aulacoseira spp., with valve densities >1.0 × 109 valves/g with a maximum biovolume of 3.5 × 1012 μm3/g. A similar planktonic assemblage was observed at much lower abundances (<107valves/g) in the deeper sediments (>1 Ma), during the earliest stages of lake formation. Two periods of increased benthic primary production of approximately ~11 kyr in duration, originating from the littoral zone of the lake, were also observed, one between the two planktonic phases and one above the last planktonic maxima. The benthic periods were dominated by Cymbopleura spp., with valve densities of approximately 2.0 × 108 valves/g and a maximum biovolume of 1.2 × 1011 μm3/g. Nonmetric multidimensional scaling analysis of sediment chemistry revealed that the benthic and pelagic states clustered with distinct chemical environments. The benthic phases were associated with well-mixed conditions in the lake whereas the planktonic phases were related to rapidly reoccurring water column mixing followed by intense stratification that generate nutrient recycling events. We conclude that lake mixing and nutrient cycling regimes regulated, in part, the switch between benthic and pelagic states in Lake Towuti.

Original languageEnglish (US)
Article number110937
JournalPalaeogeography, Palaeoclimatology, Palaeoecology
Volume594
DOIs
StatePublished - May 15 2022

Bibliographical note

Funding Information:
This project was supported by the Natural Sciences and Engineering Research Council of Canada ( NSERC) and Canada Research Chair (CRC) grants to G.D. Haffner, a Research Advisory Council (RAC) grant to P.B. Hamilton, and an Ontario Graduate Scholarship to M.K. Ageli. Further support was provided by LaCore for providing facilities to subsample the cores. The TDP was carried out with partial support from the International Continental Scientific Drilling Program (ICDP), the U.S. National Science Foundation (NSF), the German Research Foundation (DFG) the Swiss National Science Foundation (SNSF), PT Vale Indonesia, the Ministry of Research, Education, and Higher Technology of Indonesia (RISTEK), Brown University , the GFZ German Research Centre for Geosciences , NSERC, and Genome British Columbia. We thank PT Vale Indonesia, the US Continental Scientific Drilling and Coordination Office, US National Lacustrine Core Repository, and DOSECC Exploration Services for logistical support. The research was carried out with permissions from RISTEK, the Ministry of Trade of the Republic of Indonesia, the Natural Resources Conservation Center (BKSDA), and the Government of Luwu Timur of Sulawesi. Cores and project data are archived at the National Lacustrine Core Repository, USA. We would especially like to thank the three reviewers and the editor for their excellent, constructive comments and suggestions.

Funding Information:
This project was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) and Canada Research Chair (CRC) grants to G.D. Haffner, a Research Advisory Council (RAC) grant to P.B. Hamilton, and an Ontario Graduate Scholarship to M.K. Ageli. Further support was provided by LaCore for providing facilities to subsample the cores. The TDP was carried out with partial support from the International Continental Scientific Drilling Program (ICDP), the U.S. National Science Foundation (NSF), the German Research Foundation (DFG) the Swiss National Science Foundation (SNSF), PT Vale Indonesia, the Ministry of Research, Education, and Higher Technology of Indonesia (RISTEK), Brown University, the GFZ German Research Centre for Geosciences, NSERC, and Genome British Columbia. We thank PT Vale Indonesia, the US Continental Scientific Drilling and Coordination Office, US National Lacustrine Core Repository, and DOSECC Exploration Services for logistical support. The research was carried out with permissions from RISTEK, the Ministry of Trade of the Republic of Indonesia, the Natural Resources Conservation Center (BKSDA), and the Government of Luwu Timur of Sulawesi. Cores and project data are archived at the National Lacustrine Core Repository, USA. We would especially like to thank the three reviewers and the editor for their excellent, constructive comments and suggestions.

Publisher Copyright:
© 2022

Keywords

  • Ancient lakes
  • Diatoms
  • Evolution
  • Lake Towuti
  • Paleolimnology
  • Primary production

Continental Scientific Drilling Facility tags

  • TDP

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